1. Field of the Invention
This invention relates to a valve system for brass musical instruments, and, to a valve system in which a single valve is utilized to switchover more than one by-pass pipe independently to connect with the basic pipe of the instrument.
2. Description of the Prior Art
Conventional valve systems for brass musical instruments employ a valve mechanism composed of three or four separate valves placed in the basic pipe L between the mouthpiece and the bell, each of which valves is equipped with its own by-pass pipe and each of which has its own operation or tuning key so that each valve key when pressed switches to connect its own by-pass pipe to the basic pipe of the instrument.
In such conventional systems, supposing the basic pipe L is 1000 units long, most commonly the first by-pass pipe l.sub.1 controlled by the second valve is about 59 units long, which lowers the tone about a semi-tone when the pipe l.sub.1 is added to L; the second by-pass pipe or loop l.sub.2 controlled by the first valve is about 122 units long which lowers the tone about two semi-tones when it is added to L; the third by-pass circuit l.sub.3 controlled by the third valve is about 189 units long which lowers the tone about three semi-tones lower when it is added to L; and the fourth by-pass loop l.sub.4 controlled by the fourth valve in a four valve device is about 335 long which lowers the tone of the instrument about five semi-tones when it is added to L.
When the valve operating, or tuning keys are pushed certain by-pass pipes are combined by the switchover of the valves, and a tone scale of seven semi-tones from C to G.sup..music-flat. can be obtained as described in following Table 1, where three valves are used.
Table 1 ______________________________________ ratio of the real length of tuning the whole temper- key tone by-pass by-pass ament aber- pattern name circuit circuit ratio ration ______________________________________ O O O C (L) 1000 1000 O O B l.sub.1 1059 1059 0 O O B.music-flat. l.sub.2 1122 1122 0 O A l.sub.1, l.sub.2 1181 1189 8 O O l.sub.3 1189 1189 0 O A.music-flat. l.sub.3, l.sub.1 1248 1260 12 O G l.sub.3, l.sub.2 1311 1335 24 G.music-flat. l.sub.3, l.sub.1, l.sub.2 1370 1414 44 ______________________________________
A scale consisting of 12 semi-tones from C to D.sup..music-flat. can be obtained when four valves are employed. These scales, however, do not necessarily coincide with the 12 temperament scale which is desired and the more by-pass pipes are combined, the larger the aberration from temperature becomes.
These aberrations arise from the difference between the real length of the whole pipe composed of the basic pipe L and some by-pass pipes and the ideal length of pipe, or temperament ratio, required for each pitch.
To avoid these aberrations, many improvements have been suggested, or used, such as making the real length of the pipe, including added by-pass pipes, correspond to the ideal length by increasing the number of valves, and by increasing the number of by-pass pipes to be added to the basic pipes, or by using a U-type trigger device together with appropriate fingering of tuning keys. But these alleged improvements are accompanied by disadvantages such as enlargement of the device as a whole and complications in playing the instruments. The bigger a brass instrument is, the greater these defects are.